spt-switch-threshold (IPv4)
Function
The spt-switch-threshold command sets the rate threshold of the multicast packets when the Designated router (DR) at the member side joins the shortest path tree (SPT).
The undo spt-switch-threshold command restores the default value.
Format
spt-switch-threshold { traffic-rate | infinity } [ group-policy basic-acl-number [ order order-value ] ]
undo spt-switch-threshold { traffic-rate | infinity } [ group-policy basic-acl-number ]
Parameters
| Parameter | Description | Value |
|---|---|---|
| traffic-rate | Specifies the threshold rate for the switchover from the RPT to the SPT. | The value is an integer that ranges from 1 to 4194304, in kbit/s. |
| infinity | Indicates that the SPT switchover is never enabled. | - |
| group-policy basic-acl-number | Specifies an entry of the group-policy list. It works with the multicast group that matches group-policy basic-acl-number to enable the threshold. basic-acl-number specifies the number of the basic ACL that defines the range of multicast groups. | If the parameter is not set, the threshold is applied to all multicast groups. The value ranges from 2000 to 2999. |
| order order-value | Adjusts the order of the ACLs in the group-policy list. | If a group matches multiple ACLs, the threshold is selected in the order specified by order-value. order-value specifies the updated number. It is an integer. The value is any value other than original one in the current group-policy list. If the parameter is not set, the order of the ACLs in the group-policy list does not change. |
Usage Guidelines
By default, the system performs SPT switchover on receiving the first multicast data packet through the rendezvous point tree (RPT).
The Rendezvous Point (RP) and the DR at the member side periodically check the rate of passing multicast packets. This command is valid to all FWs that may function as the DR at the member side, but is invalid to RPs.
If this command is used several times for the same group, the command that is first matched according to the order takes effect.
At first, the source DR encapsulates a multicast packet in a Register message and unicasts it to the RP. The RP then sends it to receivers along the RPT.
If the threshold is configured on the DR at the host side, the DR sends a Join message to the source when the rate for transmitting the multicast packet exceeds the threshold. FWs along the path join the SPT. The subsequent multicast packets are sent to receivers along SPT. If infinity is set, the SPT cannot be set up.
To adjust the order of ACLs in group-policy list, do as follows:
Specify the ACL by using the group-policy acl-number command
Set the value of an order by using the order order-value command to insert the ACL in the position of order-value in group-policy table.
The orders of the other ACLs in the group-policy table do not change.
To add a new ACL to the group-policy list, specify group-policy basic-acl-number and order order-value. You can then insert the ACL in the position of order-value in the group-policy table. The value of order-value ranges from 1 to the value obtained by the maximum sequence number of the current group-policy plus 1. If order order-value is not specified, the ACL is inserted at the end of the group-policy list.
Users can adjust the sequence of group-policy by using order. The system selects the SPT switchover threshold according to the sequence of group-policy. This greatly improves the efficiency.
The spt-switch-threshold command and the acl command are used together. In the ACL view, you can set the address range of multicast groups to be configured with the rate threshold by specifying the source parameter in the rule command.
Example
# Set the threshold to 4 kbit/s. If the transmission rate of packets from the source to the multicast group is higher than the threshold, the FW switches packets to the SPT towards the source.
<sysname> system-view
[sysname] multicast routing-enable
[sysname] pim
[sysname-pim] spt-switch-threshold 4
# Add a group-policy: the ACL number, threshold, and order of the group-policy are 2010, 100 kbit/s, and 1 respectively.
<sysname> system-view [sysname] acl number 2010 [sysname-acl-basic-2010] rule permit source 10.1.1.2 0 [sysname-acl-basic-2010] quit [sysname] multicast routing-enable [sysname] pim [sysname-pim] spt-switch-threshold 100 group-policy 2010 order 1